The Early Jurassic A-type granites in northern Guangxi, China: Petrogenesis and implications

被引：7

作者：

Jia, Xiaohui ^{[1
]}

Wang, Xiaodi ^{[1
]}

Yang, Wenqiang ^{[1
]}

Niu, Zhijun ^{[1
]}

机构：

[1] Wuhan Institute of Geology and Mineral Resources, China Geological Survey

来源：

Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | 2014年 / 39卷 / 01期

关键词：

A-type granite; Basaltic magma underplating; Early Jurassic; Extension; Geochemistry; Petrology;

D O I：

10.3799/dqkx.2014.003

中图分类号：

学科分类号：

摘要：

The Yuanshishan granites have large amounts of mafic enclaves. This paper presents new zircon LA-ICP-MS U-Pb age, and the age analysis shows that the granites were generated in Early Jurassic (179±2 Ma).These granites are characterized by uniform silicon contents, enriched in alkali contents and more enriched in K contents, and enriched in iron and depleted in magnesium contents, with high 104×Ga/A1 values and Zr+Nb+Ce+Y contents. The granites belong to A-type granite. The Yuanshishan granites have homogeneous Sr-Nd isotope compositions (ISr=0.7017 to 0.7108, εNd(t)=-7.77 to -4.55). Mafic enclaves show lower Isr(0.7050 to 0.7071) and higher εNd(t)(-4.87 to -2.63) values. In situ zircons Hf isotope compositions from these granites have limited ranges (176Hf/177Hf)i=0.28262 to 0.28270), εHf(t)=-1.68 to 1.17, and TDM2=1.25 to 1.43 Ga. We suggest that the Yuanshishan granites were likely generated by partial melting of newly underplated basaltic lower crust in extension setting. Since Early Jurassic (~200 Ma), extension has been the major subject of the tectonic background in the interior of the South China. Multistage basaltic magma underplating is direct inducement to the Yanshanian extension. During the Early Jurassic, the South China interior was most likely in post-collisional setting.

引用

页码：21 / 36

页数：15

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